Heretofore, in order to improve wet performance of a vehicle tire, the tread portion thereof is provided with sipes so that the edges of the sipes can generate frictional force and exert an edge effect during running on wet road surfaces to thereby improve wet grip performance of the tire.
In order to further improve the wet performance, it is conceivable to increase the number of the sipes. However, as the sipes decrease the rigidity of ground contacting land regions of the tread portion, there is a possibility that steering stability of the tire is deteriorated.